Pandemics may come, with loss of biodiversity, loss of wild habitat

DESTRUCTION OF HABITAT AND LOSS OF BIODIVERSITY ARE CREATING THE PERFECT CONDITIONS FOR DISEASES LIKE COVID-19 TO EMERGE

As habitat and biodiversity loss increase globally, the novel coronavirus outbreak may be just the beginning of mass pandemics ENSIA, John Vidal 18 Mar 20, “……… Only a decade or two ago it was widely thought that tropical forests and intact natural environments teeming with exotic wildlife threatened humans by harboring the viruses and pathogens that lead to new diseases in humans like Ebola, HIV and dengue.

But a number of researchers today think that it is actually humanity’s destruction of biodiversity that creates the conditions for new viruses and diseases like COVID-19, the viral disease that emerged in China in December 2019, to arise — with profound health and economic impacts in rich and poor countries alike. In fact, a new discipline, planetary health, is emerging that focuses on the increasingly visible connections among the well-being of humans, other living things and entire ecosystems.

Is it possible, then, that it was human activity, such as road building, mining, hunting and logging, that triggered the Ebola epidemics in Mayibout 2 and elsewhere in the 1990s and that is unleashing new terrors today?

“We invade tropical forests and other wild landscapes, which harbor so many species of animals and plants — and within those creatures, so many unknown viruses,” David Quammen, author of Spillover: Animal Infections and the Next Pandemic, recently wrote in the New York Times. “We cut the trees; we kill the animals or cage them and send them to markets. We disrupt ecosystems, and we shake viruses loose from their natural hosts. When that happens, they need a new host. Often, we are it.”

Increasing Threat

Research suggests that outbreaks of animal-borne and other infectious diseases like Ebola, SARS, bird flu and now COVID-19, caused by a novel coronavirus, are on the rise. Pathogens are crossing from animals to humans, and many are now able to spread quickly to new places. The U.S. Centers for Disease Control and Prevention (CDC) estimates that three-quarters of “new or emerging” diseases that infect humans originate in nonhuman animals.

Some, like rabies and plague, crossed from animals centuries ago. Others, like Marburg, which is thought to be transmitted by bats, are still rare. A few, like COVID-19, which emerged last year in Wuhan, China, and MERS, which is linked to camels in the Middle East, are new to humans and spreading globally.

Other diseases that have crossed into humans include Lassa fever, which was first identified in 1969 in Nigeria; Nipah from Malaysia; and SARS from China, which killed more than 700 people and traveled to 30 countries in 2002–03. Some, like Zika and West Nile virus, which emerged in Africa, have mutated and become established on other continents.

Kate Jones, chair of ecology and biodiversity at UCL, calls emerging animal-borne infectious diseases an “increasing and very significant threat to global health, security and economies.”

Amplification Effect

In 2008, Jones and a team of researchers identified 335 diseases that emerged between 1960 and 2004, at least 60% of which came from non-human animals.

Increasingly, says Jones, these zoonotic diseases are linked to environmental change and human behavior. The disruption of pristine forests driven by logging, mining, road building through remote places, rapid urbanization and population growth is bringing people into closer contact with animal species they may never have been near before, she says.

The resulting transmission of disease from wildlife to humans, she says, is now “a hidden cost of human economic development. There are just so many more of us, in every environment. We are going into largely undisturbed places and being exposed more and more. We are creating habitats where viruses are transmitted more easily, and then we are surprised that we have new ones.

Jones studies how land use change contributes to the risk. “We are researching how species in degraded habitats are likely to carry more viruses which can infect humans,” she says. “Simpler systems get an amplification effect. Destroy landscapes, and the species you are left with are the ones humans get the diseases from.”

“There are countless pathogens out there continuing to evolve which at some point could pose a threat to humans,” says Eric Fevre, chair of veterinary infectious diseases at the University of Liverpool’s Institute of Infection and Global Health. “The risk [of pathogens jumping from animals to humans] has always been there.”

The difference between now and a few decades ago, Fevre says, is that diseases are likely to spring up in both urban and natural environments. “We have created densely packed populations where alongside us are bats and rodents and birds, pets and other living things. That creates intense interaction and opportunities for things to move from species to species,” he says.

Tip of the Iceberg

“Pathogens do not respect species boundaries,” says disease ecologist Thomas Gillespie, an associate professor in Emory University’s Department of Environmental Sciences who studies how shrinking natural habitats and changing behavior add to the risks of diseases spilling over from animals to humans……… https://ensia.com/features/covid-19-coronavirus-biodiversity-planetary-health-zoonoses/

@john_vidal